Year	Percent
1978	4.56
1979	4.46
1986	6.34
1987	5.26
1988	4.3
1989	3.99
1990	3.69
1991	3.2
1992	3.08
1993	4.29
1994	5.77
1995	6.12
1996	6.21
1997	5.73
1998	4.21
1999	4.18
2000	3.4
2001	3.41
2002	4.01
2003	5.77
2004	5.8
2005	7.24
2006	7.33
2007	7.75
2008	7.22
2009	9.24
2010	10.67
2011	11.93
2012	14.69
2013	15.51
2014	12.71
2015	11.19
2016	10.03
2017	7.88
2018	6.13
2019	5.66
2020	5.98